Water heater and control therefor



April 1966 H. R. KINSELLA, JR 3,246,119

WATER HEATER AND CONTROL THEREFOR Original Filed Sept. 24, 1962 I //v l fwrae HOW/4P0 44/755,416

3,246,119 WATER HEATER AND CONTROL THEREFOR Howard R. Kinselia, Jr., Atfton, Mo., assignor to White- Rodgers Company, St. Louis, Mo., a corporation of Missouri Original application Sept. 24, 1962, Ser. No. 225,606, now Patent No. 3,162,752, dated Dec. 22, 1964. Divided and this application May 11, 1.964, Ser. No. 366,480

' 1 Claim. (Cl. 219-321) This application is a division of my earlier copending application, Serial No. 225,606, filed September 24, 1962, now Patent No. 3,162,752.

This invention relates to domestic water heaters having electrical resistance heating elements and particularly to an arrangement wherein automatic control means operates the heating elements at a predetermined normal electrical load but permits operation at a somewhat higher electrical load to partially restore the preselected water tempearture under conditions wherein an unusually large drawolf of hot water results in a drop in water temperature below a predetermined point.

Being confronted with wide variations in electrical load, with outstanding peak periods, many suppliers of electrical power have imposed limitations on power use in connection with domestic water heaters. While such limitations may cause no appreciable inconvenience under conditions of normal water usage, an objectionable delay in replenishing the hot water supply may result when the occasionally large drawoif of hot water occurs. Based on the proposition that the occasional large drawoff is a relatively infrequent random occurrence not likely to appreciably increase the usual periodic load peaks, I have provided an electric water heater including automatic means whereby the electrical load is temporarily increased above the usual power supply limitation for a period sufficient to partially restore the preselected water temperature under conditions wherein the water temperature drops to a point considerably lower than that which would result from the usual drawolT.

In the drawing:

The sole figure of the drawing schematically illustrates a domestic water heater with associated electrical heating elements and controls therefor constructed in accordance with the present invention.

Referring to the single figure of the drawing, numeral 10 indicates a vertically arranged water tank having a lower fitting 12 to which a cold water line 14 is connected and an upper fitting 16 to which a hot water line 18 is connected. The tank is provided with an upper electrical resistance heater illustrated at 20 and a lower resistance heater 22. The heaters 20 and 22 may be of any suitable type and construction and preferably encircle the tank in heat conductive relationship therewith.

Arranged near the upper end of the tank are thermostats 24 and 26 and arranged near the lower end of the tank is a thermostat 28. Each of the thermostats consists of a bimetal disc 30 in good heat transfer relationship with the tank. The discs 30 have a hot position, as shown, in which they are outwardly convex and a cold position in which they are outwardly concave, which latter position they assume in response to predetermined decreases in temperature. The action from one position to the other is a snap action. Each of the thermostats is further provided with rod 32 operatively connected at one end to the center of disc 30 and carrying at its other end a switch blade 34. In thermostat 24 the switch blade 34 cooperates with two opposed pairs of stationary contacts 36-38 and 40-42. In thermostats 26 and 28 the blade 34 cooperates with single pairs of Stationary contacts 44-46 and 48-50, respectively. Thermostat 24 United States Patent 0 is therefore a double pole, double throw thermostatic switching device, and thermostats 26 and 28 are double pole, single throw devices.

Circuit connections connecting heating elements 20 and 22 with power source terminals 52 and 54 will now be described. Upper resistance heater 20 is connected across the power source terminals 52 and 54 through a lead 56, contacts 40-42 and switch blade 34 of thermostat 24, a lead 58, a lead 60, and a lead 62. Lower heating element 22 is connected across terminals 52 and 54 through the lead 56, a lead 64, contacts 36-38 and switch blade 34 of thermostat 24, a lead 66, a lead 68, contacts 48-50 and blade 34 of thermostat 28, and lead 62.

A second circuit provides energization of element 22 when thermostats 24, 26, and 28 are all in a cold position with contacts 36-38 open and contacts 44-46 and 48-50 closed. This circuit extends from terminal 54 through lead 56, lead 64, lead 70, contacts 44-46, lead 72, lead 66, lead 68, contacts 48-50, and lead 62 to terminal 52.

In operation Thermostats 24, 26, and 28 are all shown in a hot or open position, which they assume when the temperature of the water in tank 10 attains the desired temperature. The calibration or temperature settings of upper thermostat 24 and lower thermostat 28 may be substantially the same or lower thermostat 28 may be set to operate at a slightly lower temperature than upper thermostat 24, while the temperature setting of thermostat 26 is considerably lower than either.

When heated water is drawn from the upper part of the tank, cold water is admitted to the lower portion of the tank so that thermostat 28 senses the temperature drop first and closes first, thereby energizing lower heating element 22. If the withdrawal of heated water is light or moderate only thermostat 28 will close, and reheating will be accomplished by heating element 22 alone. If the withdrawal is continued, the inflow of cold water will subsequently lower the water tempearture at the upper part of the tank and contacts 40-42 of upper thermostat 24 will close.

Closing of contacts 40-42 effects energization of upper heating element 20, but due to separation of blade 34 from contacts 36-38, lower element 22 will be simultaneously de-energized so that now only upper element 20 is energized. If withdrawal of heated water is stopped at this point energization of upper heating element 20 will continue alone until the desired water temperature in the upper part of the tank is restored, whereupon contacts 40-42 of thermostat 24 will open and contacts 36-38 will be reclosed. Reclosing of contacts 36-38 again completes the energizing circuit for lower element 22, which now continues to operate alone until the water temperature in the lower portion of the tank is restored and thermostat 28 opens.

If withdrawal of heated water is continued considerably beyond the point which effects the closing of contacts 40-42 of thermostat 24, contacts 44-46 of thermostat 26 will close. Closing of thermostat 26 now permits the operation of lower element 22 concurrent with the opera tion of upper element 20. Closing of contacts 44-46 of thermostat 26 completes a shunt around contacts 36-38 of switch 24 which consists of the lead 70, contacts 44-46, and the lead 72. Under these conditions both elements 20 and 22 will operate until the thermostat 26 opens, thereby providing a rapid partial recovery of the desired water temperature. Following the open ing of contacts 44-46 of thermostat 26 under these con ditions, upper element 20 will now continue to operate alone until contacts 40-42 of thermostat 24 open, where- 3 after lower element'22 will operate alone until thermostat 28 opens,

I claim:

In a water heating tank having an upper electrical resistance heater and an energizing circuit therefor completed through an upper, double throw, vthermostatically operated switch when it moves to one throw vposition in response to a decrease in water temperature in the upper portion of the tank, and a lower heater and an energizing circuit therefor completed through said upper double throw switch when it moves to its other throw position in response to a rise in water temperature and through a lower, single throw, thermostatically opera-ted switch when it closes in response to a decrease in the temperature of the vwater in the lower portion of the tank, whereby either heater may operate to restore the water temperature in its respective portion of the tank but concurrent operation is prevented; the improvement branch of said lower heater energizing circuit paralleling said upper double throw switch, whereby said lower heater may be energized concurrently withsaid upper heater when said single throw switch is closed, and said second single throw switch being positioned in the upper portion of said tank and being operated to a closed position only when the water temperature in the upper portion of said tank drops substantially below that which effects the movement of said double throw switch to its one position and being reopened upon temperature rise at a point below that which effects the movement of said double throw switch to its other position.

References Cited by the Examiner UNITED STATES PATENTS 2,377,440 6/1945 Osterheld 219-4330 ,X 2,380,545 7/1945 Pankow 2,l9'330 X RICHARD M. WOOD, PrimaryExaminer.

ANTHONY BARTIS, Examiner. 

